1. Field of the Invention
The present invention relates generally to structures and assemblies for use in connection with a patient interface device, such as a respiratory mask, and a mask attachment assembly, such as a headgear having straps to retain the mask in a sealed position on a user's face. In particular, the present invention relates to a mask mounting mechanism connected to the respiratory mask and providing an attachable and detachable buckle and a clip element that is continuously rotatable around a button element, thereby providing additional convenience, ease-of-use, ease-of-adjustment and removal and improved comfort to the patient.
2. Description of the Related Art
It is well known to treat a medical disorder or to diagnose, treat or monitor the condition of the patient using medical equipment. For example, a patient may be monitored and treated for various sleep disorders in a lab or in some other setting. One such sleep disorder is sleep apnea. Obstructive sleep apnea is characterized by a collapse of the upper airways during sleep, while central sleep apnea is characterized by the suspension of all respiratory movement. Obstructive sleep apnea and central sleep apnea may be combined in a condition referred to as mixed apnea.
In order to diagnose and/or treat such medical disorders, various equipment and devices are required for successfully diagnosing and prescribing treatment. Further, there are numerous situations where it is necessary or desirable to deliver a flow of breathing gas, non-invasively, to the airway of a patient, i.e., without intubating the patient or surgically inserting a tracheotomy tube in their trachea. For example, it is known to ventilate a patient using a technique known as non-invasive ventilation. It is also known to deliver continuous positive airway pressure (CPAP) or variable airway pressure, which varies with the patient's respiratory cycle or a monitored condition of the patient, to treat a medical disorder, such as sleep apnea syndrome, in particular, obstructive sleep apnea (OSA), congestive heart failure, stroke, Cheynes-Stokes respiration, etc. Non-invasive ventilation and pressure support therapies involve the placement of a patient interface device, which is typically a nasal or nasal/oral mask, on the face of a patient to interface the ventilator or pressure support device with the airway of the patient, so that a flow of breathing gas can be delivered from the pressure/flow generating device to the airway of the patient.
Patients suffering from a pulmonary or respiratory disorder, such as obstructive sleep apnea, are often treated with a pressure support device, such as a continuous positive airway pressure (CPAP) device. A CPAP device delivers a flow of fluid to the airway of the patient throughout the patient's breathing cycle in order to “splint” the airway open, thereby preventing its collapse during sleep. In another type of treatment, bi-level positive pressure therapy is provided to the patient, in which the pressure of air delivered to the patient's airway varies or is synchronized with the patient's breathing cycle to maximize therapeutic effect and comfort to the patient. A pressure support device may also provide “bi-level” pressure support, in which a lower pressure is delivered to the patient during the patient's expiratory phase then during the inspiratory phase.
It is also known to provide an auto-titration positive pressure therapy in which the pressure provided to the patient changes based upon the detected conditions of the patient, such as whether the patient is snoring or experiencing an apnea, hypopnea, or upper airway resistance. Such a device adjusts the pressure delivered to the patient, based on whether or not the patient is snoring. For example, a pressure support device may actively test the patient's airway to determine whether obstruction, complete or partial, could occur and adjust the pressure output to avoid this result.
Other modes of providing positive pressure support to a patient are known. For example, a proportional assist ventilation mode of pressure support provides a positive pressure therapy in which the pressure of gas delivered to the patient varies with the patient's breathing effort to increase the comfort of the patient. Proportional positive airway pressure (PPAP) devices deliver breathing gas to the patient based on the flow generated by the patient.
For purposes of the present invention, the phrase “pressure support system”, “pressure support device”, or “positive pressure support” includes any medical device or method that delivers a flow of breathing gas to the airway of a patient, including a ventilator, CPAP, bi-level, PAV, PPAP, or bi-level pressure support system.
Typically, gas such as oxygen or air is delivered by a pressure generating device, which may be, in turn, in fluid communication with an oxygen tank. The oxygen flows from the source through the regulator devices, through the pressure generating device and further through a conduit into a patient interface. The pressure generating device and the conduit, such as a gas hose, are considered the patient circuit, such that a coupling assembly is required for connecting the patient circuit to the patient interface device.
In a conventional pressure support system, a flexible conduit is coupled to an exit conduit from the pressure generating device. The flexible conduit forms part of the patient circuit that carries the flow of breathing gas from the pressure generating system to the patient interface device. In a support system, the patient interface device connects the patient circuit with the airway of the patient so that the elevated pressure gas flow is delivered to the patient's airway.
In order to provide gas or, as discussed above, oxygen, to a patient, the patient must use a patient interface device, such as a nasal mask (including external cushions and/or internal prongs), nasal/oral mask, full-face mask, nasal cannula, oral mouthpiece, tracheal tube, endotracheal tube, or hood. Typically, patient interface devices include a mask shell having a cushion attached to the shell that contacts the surface of the patient. The mask shell and cushion are held in place by a headgear that wraps around the head of the patient. Together, the mask and headgear form the patient interface assembly. A typical mask attachment assembly includes headgear having flexible, adjustable straps that extend from the mask to attach the mask to the patient. Other techniques for attaching a patient interface device use a vice-like device that anchors at the front and back of the patient's head to support the mask on the user. See, e.g., U.S. Pat. No. 6,516,802.
Because such patient interface devices are typically worn for an extended period of time, a variety of concerns must be taken into consideration. For example, in providing CPAP or other positive pressure therapy to treat OSA, the patient normally wears the patient interface device all night long while he or she sleeps. In order to be successful in these applications, a patient interface needs to take into account two, often competing, goals: comfort and technical effectiveness. Failure to achieve either goal is likely to result in low efficacy. A comfortable, but technically ineffective, patient interface may achieve superior patient compliance; however, its technical ineffectiveness will minimize the therapeutic benefit achieved. Alternatively, a technically effective, but uncomfortable, patient interface may be capable of treating a patient; yet, the lack of comfort often results in low patient compliance. This also undermines the ultimate therapeutic benefit obtained by the patient. Thus, further advancements for interfacing a pressure support system to the airway of a patient are desired.
It is known to maintain such interface devices on the face of a wearer with a headgear assembly having upper and lower straps, each having opposite ends threaded through connecting elements provided on the opposite sides and top of the interface device, such as a mask. Because such masks are typically worn for an extended period of time, it is important that the headgear maintain the mask with a tight enough seal against a patient's face while minimizing discomfort. Adjustability of the mask and/or the headgear, together with increased patient comfort, is significant. However, most important is the maintenance of the seal between the mask and the user's face. According to the prior art, various headgear have been developed that position the straps in various locations with respect to the mask in order to effect this seal.
According to the prior art, various embodiments of collars and mask assemblies that allow for the variable positioning of headgear straps have been provided. For example, U.S. Pat. No. 6,412,488 to Barnett et al. discloses a collar 34 that is attachable to the mask with multiple cutouts 84 for attaching the strap of a mask thereto. Another collar device for attachment to a mask, and to allow variable positioning, is disclosed in U.S. Pat. No. 5,662,101 to Ogden et al. The Ogden assembly includes a rigid plate 9 connected to a facial mask assembly 1. Straps, such as adjustable straps 13R, 13L are inserted through the openings 29, 31 in order to secure the mask assembly 1 in a sealed position against the user's face. However, the devices of the Barnett patent and the Ogden patent, while moveable between various positions, are not fully flexible, rotatable or easily attachable and detachable to the mask.
Yet another mask mounting mechanism or collar according to the prior art is shown and described in U.S. Pat. No. 6,631,718 to Lovell, which is similar in design and operation to the Barnett device. In particular, the Lovell device includes a retainer 12, 212 that is attachable to the shell 4 of the mask. This retainer, 12, 212 includes lower connection points 14, 214 and at least one upper connection point 16, 216, as best illustrated in FIGS. 1, 2A, 7 and 9-11. While, like the Barnett device, the assembly of the Lovell patent permits multiple attachment points for variations in strap connection and positioning, the retainer 12, 212 is not rotatable about the shell 4 of the mask. Accordingly, the Lovell device is not rotatable, and does not provide flexibility in attachment. In addition, the Lovell device does not provide for the simple attachment and removal of the buckle (and, hence, the strap) to and from the mask. A similar non-rotatable and inflexible headgear/strap assembly is disclosed in U.S. Pat. No. 6,823,869 to Raje et al., such as in, e.g., FIGS. A11 and F36.
Yet another mask mounting mechanism according to the prior art is disclosed in U.S. Pat. No. 6,595,214 to Hecker et al. The Hecker et al. patent discloses a clip element in the form of an eyelet 7 extending from a mask 1 is disclosed. The Hecker mask illustrates that, as opposed to a collar attached to the mask, individual clip elements, each with a buckle or eyelet 7 thereon, can be directly attached to the mask shell. As discussed above in connection with the collar devices, the eyelets 7 (or clip elements) of the Hecker patent are permanently affixed to the mask. Accordingly, these clip elements are non-rotatable and illustrate an inflexible strap attachment assembly. In addition, it is difficult to maintain an adequate seal in these devices.